1. Field of the Invention
The present invention relates to a sealing tape and a method and apparatus for its production, and a method of repairs with it, and more particularly to a sealing tape for covering, in a car body, an exposed metal surface, a joint between metal plates, a shoulder portion in joint, and like stepped portions.
2. Description of the Prior Art
In the manufacture of automobiles, it has been the practice to apply a sealing agent to joint portions and joint shoulder portions in car bodies such as body panel joints and hemming portions in door and hoods of the car bodies to prevent water and dust from entering the car bodies. More specifically, as shown in FIG. 15, in case that an inner metal plate B is inserted into and jointed to a bent portion C of an outer metal plate xe2x80x9cAxe2x80x9d which is provided with the bent portion C in its end portion, a joint shoulder portion D extending in a direction perpendicular to the plane of the drawing paper is covered with a strip of sealing agent E having been squeezed out of a tube through its nozzle, so that the thus sealed joint shoulder portion D extends in the direction perpendicular to the drawing paper.
The application of this sealing agent E to the car body is carried out by an industrial robot during the manufacture of the car or automobile. Consequently, it is possible to control, with high accuracy, both the amount of the sealing agent E being squeezed out through the nozzle and a traveling distance of the nozzle, which enables the sealing agent E having been applied to the car body to assume a constant shape in cross section, as shown in FIG. 14. The application of the sealing agent E to the car body is followed by the application of paint.
When the joint of car body panels is deformed by an impact applied to the car, it is necessary to repair such deformed joint so as to have the joint return to its original shape in appearance.
In such repairing and paint application of the car body, after completing the repair in shape of the joint of the car body panels, the sealing agent E is applied to the joint in a manner such that: the nozzle of the tube, which is made of, for example, metal and filled with the sealing agent E, is manually brought into direct contact with a joint of the car body by an auto worker; and, the sealing agent E is also manually squeezed out of the tube through the nozzle thereof while the nozzle of the tube is manually moved along the course of the joint by the worker, whereby the application of the sealing agent E to the course of the joint is manually carried out by the worker.
In such manual operations, it is very difficult for the worker to keep constant the amount of the sealing agent E applied to the course of the joint even when he concentrates his attention on his work in which he must constantly squeeze the sealing agent E out of the tube as he moves the tube along the course of the joint. In other words, in most cases, the worker fails to accurately trace the course of the joint, which results in an uneven finishing surface of the sealing agent E thus applied to the joint. Due to this failure, the joint of the body panels thus repaired fails to assume the same shape as that of a joint of body panels in a new car. The shape of the joint in a new car is shown in FIG. 15 in cross section.
Previous to the present invention, the inventor of the subject application has already proposed a conventional sealing tape 10. This sealing tape 10 enables a user to seal the joint of car body panels with it in a very easy manner, and the joint thus sealed with the tape 10 is excellent in finishing.
As shown in FIG. 14, the conventional sealing tape 10 assumes an relatively thick strip-like shape with a stepped bottom surface, and is made of vulcanized rubber material to resiliently keep its original shape. In use, such conventional sealing tape 10 is adhesively applied to a joint shoulder portion of metal plates (See, Japanese Utility Model Registration No. 3,004,875).
For example, as shown in FIG. 13, in application of the conventional sealing tape 10 assuming the above shape to the the joint shoulder portion D located between the outer or first metal plate xe2x80x9cAxe2x80x9d and the inner or second metal plate B which is inserted into and jointed to the bent portion C of the first metal plate xe2x80x9cAxe2x80x9d which is provided with the bent portion C in its end portion, the sealing tape 10 has its first bottom surface portion 11, which is opposite to a curved portion 14 of the tape 10, and its second bottom surface portion 12, which is opposite to a flange edge portion 15 of the tape 10, adhesively applied to the metal plates xe2x80x9cAxe2x80x9d and B, respectively.
As a result, both the first bottom surface portion 11 and the second bottom surface portion 12 of the conventional sealing tape 10 may firmly adhere to the joint shoulder portion D located between the metal plates xe2x80x9cAxe2x80x9d and B, which ensures that the joint shoulder portion D is sufficiently sealed up.
However, for example, as shown in FIG. 12, when the conventional sealing tape 10 is used in a joint shoulder portion of metal plates of an inner side of a car rear door (an upholstery lining panel of which is removed in FIG. 12), it is necessary to bend the sealing tape 10 at substantially right angles in a manner such that the sealing tape 10 extends along a corner portion G of the door to adhere to the corner portion G.
In this case, the sealing tape 10 often slacks in or separate from the corner portion G of the door, which impairs the door in its surface finish quality. In order to improve the door in such surface finish quality, it is necessary to manually apply the sealing agent E to this corner portion G of the door as is in the conventional application.
The above-mentioned slacking and separation of the sealing tape 10 occurs because of its resiliency. In other words, since the sealing tape 10 is made of rubber material having been vulcanized and assumes a strip-like or elongated shape with resiliency, such slacking and separation occurs in the corner portion G of the door. In general, rubber material is vulcanized to assume a fixed shape of a desired rubber product, because rubber material not vulcanized may vary in shape under pressure. Consequently, such rubber material not vulcanized is not adequate for the purpose of the sealing tape which must keep its shape for a long period of time in use.
Under such circumstances, the present invention was made on the basis of the fact that the application of paint in car repairs is accompanied with a heating process. Consequently, it is an object of the present invention to provide a sealing tape and a method and apparatus for its production, and a method of repairs with the sealing tape which is an unvulcanized tape, and, therefore capable of freely varying in shape when required to bend, the method of repairs using the heating process to vulcanize this sealing tape.
According to a first aspect of the present invention, the above object of the present invention is accomplished by providing:
A sealing tape made of a sealing-tape material containing an unvulcanized rubber-base material and its vulcanization accelerator, the sealing tape assuming an elongated shape with a bottom surface and a predetermined thickness measured in a direction perpendicular to the bottom surface.
Since the sealing tape of the present invention is in an unvulcanized state, it is capable of being freely deformed. Consequently, even when the sealing tape of the present invention is bent into a desired shape, there no fear that the tape slacks and separates from a portion to which the tape is applied.
According to a second aspect of the present invention, the above object of the present invention is accomplished by providing:
The sealing tape as set forth in the first aspect of the present invention, wherein:
added to the unvulcanized rubber-base material together with the vulcanization accelerator is an anti-oxidizing agent.
The anti-oxidizing agent is capable of improving the sealing tape of the present invention in weatherability.
An adhesive may be applied to the bottom surface of the sealing tape, the unvulcanized state of which tape makes it possible to apply the adhesive to the bottom surface of the sealing tape.
According to a third aspect of the present invention, the above object of the present invention is accomplished by providing:
The sealing tape as set forth in the first aspect of the present invention, wherein:
the bottom surface is a stepped surface which enables the sealing tape to be brought into close- or hermetic-contact with a stepped joint or shoulder portion of metal plates.
According to a fourth aspect of the present invention, the above object of the present invention is accomplished by providing:
A method for producing a sealing tape, comprising:
a sealing-tape material preparing step for preparing a sealing-tape material containing an unvulcanized rubber-base material and its vulcanization accelerator;
a sealing-tape forming step in which the sealing-tape material is formed into a substantially square-shaped sheet while keeping its unvulcanized condition;
an adhesive applying step for applying an adhesive sheet to a bottom of the substantially square-shaped sheet, the adhesive sheet being coated with an adhesive; and
a substantially square-shaped sheet cutting step for cutting the substantially square-shaped sheet into at least one of the sealing tapes each of which assumes an elongated shape having a bottom surface and a predetermined thickness measured in a direction perpendicular to the bottom surface of the sealing tape, wherein the substantially square-shaped sheet is moved while having its upper surface brought into press-contact with a roll-type cutter provided with at least a pair of circular blades axially spaced apart from each other through an annular concave portion formed in a peripheral portion of the roll-type cutter.
In this method for producing the sealing tape, the annular concave portion of the roll-type cutter may be a circularly-curved shape in cross section which is adapted for being used.
Further, in the method for producing the sealing tape, an anti-oxidizing agent may be added in the sealing-tape material preparing step. The anti-oxidizing agent is capable of improving the unvulcanized sealing tape in weatherability.
According to a fifth aspect of the present invention, the above object of the present invention is accomplished by providing:
A method of repairs with a sealing tape, comprising the steps of:
applying the sealing tape to a joint between a pair of metal surfaces or metal plates to bond the sealing tape to the joint while bending the sealing tape, wherein the sealing tape is made of a sealing-tape material containing an unvulcanized rubber-base material and its vulcanization accelerator, the sealing tape assuming an elongated shape with a bottom surface and a predetermined thickness measured in a direction perpendicular to the bottom surface; and
applying, in a painting process, a paint to an upper surface of the sealing tape thus bent and bonded to the joint, wherein the paint is subjected to a heating process in which the sealing tape thus bent and bonded is vulcanized to become a final rubber product with a fixed resilient shape thus bent and bonded.
In this method of repairs with the sealing tape, the sealing tape has its bottom surface bonded to the joint of the metal surfaces, which is followed by the the painting process accompanied with the heating process for vulcanizing the sealing tape. Consequently, the sealing tape subjected to the hearing process is vulcanized to become a final rubber product assuming a fixed resilient shape thus bent and bonded, which enables the sealing tape thus vulcanized to resiliently keep its final shape.